1. Field of the Invention
The present invention relates generally to the production of slide fasteners, and more particularly to an apparatus for manufacturing a paper stringer tape for slide fasteners.
2. Prior Art
In the manufacture of a slide fastener having a pair of paper stringer tapes, it is a common practice to score a continuous folding line on a blank paper strip along one longitudinal margin thereof and to then fold the paper strip about the score line to provide a folded edge on which a row of thermoplastic coupling elements is to be mounted. The problem is that the scoring line varies in depth due to local thickness change of the paper strip. With this varying depth of the scoring line, it is possible to fold the paper strip only incompletely, i.e. with an elongate gap or space within the folded edge along the folding line, causing unstable and irregular attachment of the coupling elements to the folded edge.